U.S. patent number 10,439,187 [Application Number 15/644,311] was granted by the patent office on 2019-10-08 for laminar battery system.
This patent grant is currently assigned to APPLE INC.. The grantee listed for this patent is Apple Inc.. Invention is credited to George V. Anastas, Joshua R. Funamura, Jack B. Rector, III, Kenneth M. Silz, Gregory A. Springer.
United States Patent |
10,439,187 |
Anastas , et al. |
October 8, 2019 |
Laminar battery system
Abstract
A battery system comprises a plurality of substantially planar
layers extending over transverse areas. The plurality of layers
comprises at least one cathode layer, at least one anode layer, and
at least one separator layer therebetween.
Inventors: |
Anastas; George V. (San Carlos,
CA), Springer; Gregory A. (Los Altos, CA), Rector, III;
Jack B. (San Ramon, CA), Funamura; Joshua R. (San
Carlos, CA), Silz; Kenneth M. (Brentwood, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
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Assignee: |
APPLE INC. (Cupertino,
CA)
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Family
ID: |
50773573 |
Appl.
No.: |
15/644,311 |
Filed: |
July 7, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170309882 A1 |
Oct 26, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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14041843 |
Sep 30, 2013 |
9711770 |
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61730402 |
Nov 27, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
4/0404 (20130101); H01M 10/0562 (20130101); H01M
10/052 (20130101); H01M 4/0471 (20130101); H01M
10/0585 (20130101); H01M 2/1653 (20130101); H01M
2/145 (20130101); Y10T 29/49115 (20150115); H01M
2004/021 (20130101); H01M 4/0421 (20130101); H01M
6/40 (20130101); H01M 2300/002 (20130101); Y10T
29/49108 (20150115) |
Current International
Class: |
H01M
2/00 (20060101); H01M 2/16 (20060101); H01M
4/04 (20060101); H01M 10/052 (20100101); H01M
10/0562 (20100101); H01M 10/0585 (20100101); H01M
6/40 (20060101); H01M 2/14 (20060101); H01M
4/02 (20060101) |
References Cited
[Referenced By]
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Other References
Zhonghua et al., "Layered Cathode Materials Li
[NixLi(1/3-2x/3)Mn(2/3-x/d)]O2 for Lithium-Ion Batteries,"
Electrochemical and Solid-State Letters, vol. 4, No. 11, 2001, pp.
A191-A194. cited by applicant.
|
Primary Examiner: Rhee; Jane J
Attorney, Agent or Firm: Brownstein Hyatt Farber Schreck,
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of U.S. patent application Ser.
No. 14/041,843, filed Sep. 30, 2013, entitled "Laminar Battery
System," which claims the benefit under 35 U.S.C. .sctn. 119(e) of
U.S. Provisional Patent Application No. 61/730,402, filed Nov. 27,
2012, entitled "Laminar Battery System," the contents of which are
incorporated by reference as if fully recited herein.
Claims
We claim:
1. A battery assembly, comprising: a first anode current collector;
first anode active material coupled to the first anode current
collector; a first cathode current collector; first cathode active
material coupled to the first cathode current collector; a first
separator positioned between the first anode active material and
the first cathode active material; a second anode current collector
positioned adjacent the first cathode current collector without
anode active material positioned therebetween; second anode active
material coupled to the second anode current collector; a second
cathode current collector; second cathode active material coupled
to the second cathode current collector; and a second separator
positioned between the second anode active material and the second
cathode active material.
2. The battery assembly of claim 1, wherein the battery assembly
has a thickness less than 100 microns.
3. The battery assembly of claim 1, further comprising a spacer
positioned between the second anode current collector and the first
cathode current collector.
4. The battery assembly of claim 1, wherein the battery assembly
has a cathode active material stacking efficiency of at least about
30% of a thickness of the battery assembly.
5. The battery assembly of claim 1, further comprising an
encapsulant that at least partially encapsulates the first anode
current collector, the first anode active material, the first
cathode current collector, the first cathode active material, the
first separator, the second anode current collector, the second
anode active material, the second cathode active material, and the
second separator.
6. The battery assembly of claim 5, wherein portions of the first
anode current collector, the first cathode current collector, and
the second anode current collector extend through the
encapsulant.
7. The battery assembly of claim 1, wherein the first anode current
collector and the second anode current collector extend from a
surface of the battery assembly and the first cathode current
collector and the second cathode current collector extend from an
opposing surface of the battery assembly.
8. A battery core, comprising: a first anode current collector with
first anode active material coupled thereto; a cathode current
collector with cathode active material coupled thereto; a separator
positioned between the first anode active material and the cathode
active material; and a second anode current collector with second
anode active material coupled thereto positioned adjacent the
cathode current collector without anode active material positioned
between the second anode current collector and the cathode current
collector.
9. The battery core of claim 8, wherein the separator covers
multiple surfaces of the cathode active material.
10. The battery core of claim 8, wherein the separator has sloped
sides.
11. The battery core of claim 8, further comprising an ion
transport layer positioned between the second anode current
collector and the cathode current collector.
12. The battery core of claim 8, wherein the cathode active
material has a thickness of approximately 10-30 microns.
13. The battery core of claim 8, wherein the battery core has an
anode active material stacking efficiency of at least about 30% of
a thickness of the battery core.
14. The battery core of claim 8, wherein the battery core has a
thickness less than 50 microns.
15. A battery, comprising: first and second cells each comprising:
an anode current collector; anode active material coupled to the
anode current collector; a cathode current collector; cathode
active material coupled to the cathode current collector; and a
separator positioned between the anode active material and the
cathode active material; and an insulating spacer; wherein the
first and second cells are coupled such that: the cathode current
collector of the first cell is positioned adjacent the anode
current collector of the second cell; and the insulating spacer is
positioned between the cathode current collector of the first cell
and the anode current collector of the second cell.
16. The battery of claim 15, further comprising a coating of
rubber, silicone, or polymer that at least partially surrounds the
first and second cells.
17. The battery of claim 15, wherein the cathode active material
comprises at least 40% of a thickness of the battery.
18. The battery of claim 15, further comprising an electrolyte
positioned between the cathode current collector of the first cell
and the anode current collector of the second cell.
19. The battery of claim 15, further comprising a third cell
coupled to the second cell wherein the cathode current collector of
the second cell is positioned adjacent the anode current collector
of the third cell.
20. The battery of claim 15, wherein the cathode current collector
of the first cell is separated from the anode current collector of
the second cell.
21. The battery of claim 15, wherein the cathode active material is
thicker than the anode active material.
Description
TECHNICAL FIELD
The subject matter of this disclosure relates generally to
electronic devices, and specifically to battery systems for
portable electronics and mobile devices. In particular, the
disclosure relates to battery systems with particular energy
density, form factor and overall size and weight requirements.
BACKGROUND
Batteries come in a range of different architectures and forms,
including traditional rod-and-tube (dry cell) and flat plate
(flooded cell) designs, as well as "jelly roll" configurations in
which the anode and cathode layers are laid down on opposite sides
of a flat sheet or flexible substrate and rolled up for insertion
into the battery case or pouch. In flat battery designs, the rolled
anode and cathode structure is folded into a low-profile casing or
pouch, which is sealed along one or more sides.
Battery configurations for portable electronics and mobile devices
require a range of design tradeoffs, including size, weight, power
consumption, manufacturability, durability and thermal loading. In
general, the amount of energy or storage capacity per battery
weight (or volume) can also be an important factor, because a
greater energy/battery weight or volume ratio makes for a better,
longer lasting battery
SUMMARY
Exemplary embodiments of the present disclosure include battery
systems, and methods of making the battery systems. The battery
systems may comprise a plurality of substantially planar layers
extending over a transverse area. The plurality of layers may
include at least one cathode layer, at least one anode layer, and
at least one separator layer therebetween.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a battery with increased energy
density and improved form factor.
FIG. 2 is a cross-sectional view of the battery.
FIG. 3 is an enlarged cross-sectional view of the battery, showing
the laminar structure of the battery core.
FIG. 4 is an alternate cross sectional view of the battery, showing
the laminar core structure in an alternating anode/cathode layer
configuration.
FIG. 5 is a schematic diagram of a method for producing a laminar
battery core.
FIG. 6A is a cross-sectional illustration of a cathode layer for a
laminar battery core.
FIG. 6B is a cross-sectional illustration of anode and cathode
layers for the laminar battery core.
FIG. 6C is a cross-sectional illustration of a core stack element
for the laminar battery core, with anode and cathode layers, anode
collector and flexible sealant.
FIG. 7A is a schematic illustration of the laminar battery core
stack, illustrating different external connector
configurations.
FIG. 7B is a schematic illustration of the laminar battery core
stack, in a single-side stack configuration.
FIG. 7C is a schematic illustration of the single-side stack
configuration, illustrating representative layer thicknesses.
FIG. 8 is a schematic illustration of the laminar battery core
stack, in a double-sided configuration.
FIG. 9 is a schematic illustration of the laminar battery core
stack, in a single-sided, double stack configuration.
FIG. 10 is a schematic illustration of the laminar battery core
stack, in a multi-stack configuration.
DETAILED DESCRIPTION
FIG. 1A is a perspective view of battery assembly 10 with pouch or
outer casing 12 and protective wrap or film 14, which may be used
for shipping, or for protection from damage and corrosion. An
encapsulant or other sealing material 16 may be utilized to seal
battery casing 12 to prevent leakage of electrolytes and other
materials from the inside of battery assembly 10, to inhibit
moisture intrusion, and to reduce oxidation and corrosion of the
anode and cathode surfaces.
In the particular configuration of FIG. 1, battery assembly 10 has
a substantially oblong or rectangular geometry or form factor, with
width W defined between opposite sides 18A and 18B, length L
defined between opposite sides or ends 19A and 19B, and thickness T
defined between opposite major surfaces 20A and 20B. The battery
core is provided within casing 12, and is configured for increased
energy density, as described below, within an improved form factor
(or volume envelope), as defined by length L, width W and thickness
T.
Length L and width W are typically measured along first and second
major surfaces 20A and 20B of battery system 10, in the direction
of (horizontal) axes x and y, excluding the thickness of protective
wrapper or film 14. Similarly, height or thickness T is measured
between major surfaces 20A and 20B, along (vertical) axis z, also
excluding protective wrapper 14.
In low-profile or flat configurations of battery assembly 10,
thickness T is generally less than length L or width W, so that
major surfaces 20A and 20B have substantially greater surface area
than side and end surfaces 18A, 18B. 19A and 19B. The orientation
of coordinate axes x, y, and z is arbitrary, however, and the
various dimensions of length L, width W, and thickness T may also
be interchanged, depending on configuration.
Connector 22 provides electrical power and signal connections to
battery assembly 10, for example in a "pig tail" configuration with
a connector board 23 coupled to battery assembly 10 via flex
circuit 24, as shown in FIG. 1. Depending on application, connector
22 and flex circuit 24 may be configured to accommodate a range of
different connection geometries, for example along a side surface
(e.g., side 18A or 18B) or an end surface (e.g., end 19A or 19B) of
battery casing 12, or at a corner interface (e.g., between side 18A
and end 19A, as shown in FIG. 1).
Where battery dimensions including length L, width W, and thickness
T are constrained, increased energy density provides battery system
10 with greater storage capacity within a given form factor, and
longer service life between charges. Increased energy density also
allows for reducing the form factor at a given storage capacity, or
a combination of increased capacity and reduced battery dimensions,
for overall improvements in both battery life and form factor or
size envelope.
FIG. 2 is a cross-sectional view of battery system (battery
assembly or battery) 10, taken along line 2-2 of FIG. 1. Battery
case or pouch 12 is formed about inner battery element or core 28,
which stores electrical energy and provides voltage and current.
Protective wrapper 14 may be formed of an thin polymer sheet, for
example a polyethylene terephthalate (PET) film, and provided to
cover battery 10 during shipping, for example utilizing insignia
14A for identification.
Battery casing 12 is typically formed of a laminated material, for
example an aluminum alloy core layer 12A with plastic or polymer
insulating layers 12B and 12C on the inner and outer surfaces.
Typically, core layer 12A provides strength, durability and
structural integrity, and while coating layers 12B and 12C provide
electrical insulation and chemical protection from caustic
materials in battery core 28, for example acid or alkali
electrolytes or other active components 28A. Alternatively, battery
casing 12 may be formed of a polymer material, or using an
encapsulant, conformal coating or sealant material, for example as
described with respect to sealing material 16.
Battery core 28 comprises a laminated structure, as shown in FIG.
2, with active materials 28A interspersed between inactive or
passive materials 28B. Active materials 28A include at least one or
both of the cathode and anode layers, as described in more detail
below. Inactive materials 28B may include spacers, insulators or
substrate materials, which separate the anode and cathode pads.
Although three layers of active material 28A and two spacer layers
28B are shown, the number of individual layers varies, depending on
the design of battery system 10 and battery core 28, and additional
or fewer layers are contemplated.
To improve the energy density and storage capacity of battery
system 10, battery core 28 is provided with an improved laminated
structure to increase the relative volume of active materials 28A,
as compared to inactive or passive (spacer) materials 28B. This
also contrasts with rolled battery core designs, for example, where
there are substantial side roll regions, with relatively low energy
density. In the laminar structure of battery core 28, on the other
hand, active and passive layers 28A and 28B are substantially
planer across most or substantially of the full length and width
(that is, transverse area) of battery core 38, including end
regions 30.
This laminar and substantially planar configuration for battery
core 28 substantially reduces spacing issues presented by building
anode and cathode layers into a rolled core configuration, where
(1) there is a substantial amount of side roll that does not
significantly contribute to battery capacity, and (2) there is a
substantial spacing between the anode and cathode pads, which is
required to prevent shorting in the high curvature side roll
regions.
In contrast, active and passive layers 28A and 28B of battery core
28 are substantially flat and planar across substantially the full
length and width of battery assembly 10, as shown in FIG. 2,
increasing capacity by providing relatively more substantially
planar area in battery core 28, with relatively higher energy
density and more efficient energy storage. The substantially
planar, laminar configuration of battery core 28 also reduces the
non-planar side roll areas, as provided in a rolled core design,
and which have relatively lower energy density and relatively less
efficient energy storage. These effects may be particularly
relevant in flat-profile form factor designs, as shown in FIGS. 1
and 2, where the side roll curvature is high, and only the
relatively straight or planar portions of the battery core
significantly contribute to overall battery capacity and storage
capability.
Laminar, substantially planar battery core 28 also reduces the
required spacing between the anode and cathode pads, because
tolerance is easier to maintain across the flat-plane structure of
active and passive material layers 28A and 28B, as compared to a
rolled design, with reduced risk of the anode and cathode pads
accidentally touching, and shorting out the battery. This also
increases energy storage density, by providing more active material
28A per unit volume of battery core 28, including relatively more
cathode thickness or volume, as compared to passive material
28B.
FIG. 3 is an enlarged cross-sectional view of battery 10, showing
the internal laminar structure of battery core 28. As shown in FIG.
3, battery core 28 is formed with alternating layers of active
material 28A and passive materials 28B, for example insulators or
substrates, positioned between upper and lower portions of battery
casing 12, and encapsulated with an epoxy, polymer, or other
encapsulating material 16.
Battery casing 12 provides a mechanical, electrical and chemical
barrier to isolate battery core 28 of battery 10, as described
above. Depending on embodiment, battery casing 12 may extend along
the sides of battery core 28, as shown in FIGS. 1 and 2, or
encapsulating material 16 may be exposed on the sides, as shown in
FIG. 3. Encapsulating material 16 may also be provided in a range
of different thicknesses, and applied either across the full height
or thickness of battery core 28, as shown on the left side of FIG.
3, or distributed across individual layers 28A of active material,
as shown in the right side of FIG. 3.
Active material 28A is formed of anode layers 32 and cathode layers
34, spaced apart by separator layers 36. Pads or conductor
(collector) layers 37 and 39 are provided adjacent anode and
cathodes 32 and 34, respectively. As shown in FIG. 3, the top and
bottom anode/cathode structures have an inverted or double-sided
stack orientation, with adjacent cathode layers 34 separated by a
single anode pad layer 39.
Thus, three layers of active material 28A are shown, including two
anode layers 32 and two cathode layers 34, separated by two spacer
layers 36. Alternatively, additional or fewer anode, cathode,
spacer, and collector layers 32, 34, 36, 37, and 39 may be
included. In additional configurations, collector layers 37 and 39
may be defined as either active or passive material, in which case
the example of FIG. 3 could be considered to have three or four
active layers 28A, and two or three passive or inactive layers
28B.
Anode layers 32 and cathode layers 34 are formed of suitable anode
and cathode materials including, but not limited to, lithium cobalt
oxide, lithium iron phosphate, lithium manganese oxide, lithium,
lithium metal phosphates, carbon, and graphite, for example
graphite infused with lithium ions. In one particular
configuration, for example, anode layer 32 is formed of lithium,
and cathode layer 34 is formed of lithium cobalt oxide.
Alternatively, anode layer 32 may be formed of lithium cobalt
oxide, or another lithium or metal oxide material, and cathode
layer 34 may be formed of graphite. Depending on the charging or
discharging state of battery 10, moreover, charge flow in anode and
cathode layers 32 and 34 may reverse, as described below, without
loss of generality.
Separator layer 36 is formed of a suitable insulating separator
material that is permeable to ion transport, for example a porous
polymer or microporous polyethylene lithium ion transport material,
or a paper or fibrous composite material.
Anode and cathode pads or collector layers 37 and 39 may be formed
of suitable conducting metals such copper or aluminum.
Alternatively, the lithium anode may be utilized, at least charge
transport inside batter core 28.
Separator layer 36 may be permeated with an electrolyte having
suitable ion transport properties, for example ethylene carbonate
or diethyl carbonate containing lithium ion complexes. In lithium
and lithium ion applications of battery 10, the electrolyte is
typically non-aqueous, in order to avoid reacting with any lithium
metal components of battery core 28.
Carbon nanotube materials may also be used, for example extending
from the anode base (layer 32 or 37), so that lithium ions are
maintained by attachment to the (conducting) carbon nanotube
material. This contrasts with other designs, were lithium may be
eaten away or otherwise lost from anode layer 32 or anode collector
(or pad 37), raising the risk of a short or other battery fault.
Where a sufficient level of lithium is maintained, using carbon
nanotubes or other lithium retention elements in one or both of
anode layer 32 and anode collector layer 37, battery 10 remains
effective over periods of extended use, including repeated charge
and drain cycles.
In discharge operations of battery 10, for example oxidation may
take place in anode layer 32, so that anode layer 32 functions as a
negative electrode. Thus, anode collector 37 may have a relatively
negative charge, providing electron flow to the external circuit.
Reduction reactions may take place in cathode layer 34, so that
cathode layer 34 functions as a positive electrode. Thus, cathode
collector 39 may have a relatively positive charge, accepting
electron flow from the external circuit. In secondary battery
systems 10, recharging operations may be supported, where the
current flow and oxidation reduction reactions are reversed. The
charge flow in (or designations of) anode layer 32 and cathode
layer 34 may also be reversed, depending on usage and nomenclature,
and as described above.
FIG. 4 is an alternate cross-sectional view of battery 10, showing
the internal laminar structure of battery core 28 in a non-inverted
or single-sided stack configuration. In this design, anode layers
32 and cathode layers 34 alternate across the height of battery 10,
between top and bottom battery casings 12. An additional insulating
spacer layer 40 is provided between adjacent anode carrier layer 37
and cathode carrier layer 39. Again, the number of individual
layers is arbitrary, and may be increased or decreased depending on
layer thickness, battery configuration, and battery form
factor.
The design of FIG. 4 has a substantially uniform layering
configuration, with separate anode and cathode carrier layers 37
and 39 for each anode layer 32 and cathode layer 34, respectively.
An additional spacer, insulator, or insulating substrate layer 40
may be included, adding to the relative volume of passive material
layers 28B, but any such increase may be relatively nominal because
the planar structure of battery core 28 does not require additional
spacing tolerance to accommodate high curvature end regions, as
characteristic of rolled battery core designs.
For example, in some rolled battery core designs, a minimum
tolerance of about 20 microns or more is required between adjacent
anode and cathode pads or carrier layers 37 and 39, in order to
reduce the risk of shorting in end-roll regions with high
curvature. In other designs, the required tolerance may be even
greater, for example more than about 50 microns, or even more than
about 100 microns. In the substantially planar configuration of
battery core 28, however, there is little or substantially no
curvature, and the minimum required thickness for inter-pad
(insulation) layer 40 may be less than 20 microns, for example
about 10 microns or less, or about 8 microns or less.
FIG. 5 is a schematic diagram of method 50 for producing a laminar
battery core, for example laminar core 28 of battery assembly 10,
as shown in FIGS. 1-4, and as described above. Method 50 includes
one or more steps selected from deposition (step 51), baking or
annealing (step 52), encapsulation (step 53), adding electrolyte
and separator (step 54), and completing the battery core or core
stack element (step 55).
Deposition (step 51) may include depositing an anode slurry on an
anode collector or anode collector substrate, depositing a cathode
slurry on a cathode collector or cathode collector substrate, or
both. The lateral dimensions of the deposited anode and cathode
materials may be defined by positioning a screen or electrode mask
with respect to the collector substrates. The thickness or depth d
of the anode and cathode layers may be controlled by translating a
silkscreen blade or other mechanical element across the mask or
screen, as illustrated in step 51 of FIG. 5.
Baking/Annealing (step 52) may include heating the mask or masks
with the anode or cathode slurry materials in order to anneal or
harden the materials into a suitable form for use in a battery or
battery core stack. Depending on embodiment, a nickel iron alloy
such as INVAR or KOVAR may be utilized for the mask, or another
material with a low or particularly selected (matched) coefficient
of thermal expansion (CTE), in order to maintain particular
dimensions with respect to the anode and cathode material during
the heating in step 52, and in any subsequent cooling process.
Encapsulation (step 53) may include removing the electrode mask and
positioning a secondary or encapsulation mask with respect to the
anode or cathode layers, and/or the corresponding collector
substrates. An encapsulant such as a thermoplastic or other polymer
may then be deposited about the anode and cathode layers based on
the encapsulation mask geometry. The encapsulant may be cured by
heating, ultraviolet radiation, or chemical means. Alternatively, a
self-curing encapsulant compound may be utilized, for example an
epoxy resin.
Electrolyte and separator components are added in step 54. For
example, a permeable separator material may be applied to either or
both of the anode or cathode layer, and the separator material may
be saturated or permeated with an electrolyte material. Additional
encapsulant may also be applied along the separator layer.
In step 55, the anode and cathode layers are joined in an adjacent
relationship to form a laminated battery core element, with the
electrolyte-permeated separator positioned between adjacent anode
and cathode layers, and the electrode and cathode collector layers
positioned on the electrode and cathode layers, respectively. In
general, the collector layer may be positioned opposite the
separator layer, as defined across the respective anode and cathode
layers.
The individual core stack elements can be assembled in a variety of
different configurations to form the battery core, for example as
described above with respect to FIGS. 3 and 4, above, and in FIGS.
6A-6C, 7A-7C, and 8-10, below. Suitable techniques include, but are
not limited to, optical positioning, robotic positioning, optical
device assembly techniques, and other suitable positioning
techniques for assembly battery core or core stack 28.
The laminated core structure of battery 10 and method 50 provides a
more uniform battery core structure than a rolled battery design,
with more precise control of critical dimensions including
individual layer thicknesses. By reducing thickness requirements in
the separator and other passive or inactive components, moreover,
energy density is increased, for improved performance within a
given form factor or volume envelope.
Battery lamination method 50 also provides a greater selection
range for individual (active and passive) layer thicknesses,
including thicker active anode and cathode layers. In thicker and
"superthick" embodiments, the battery core is more "z efficient,"
with a higher density of active materials along the vertical
(thickness) dimension of the battery core, perpendicular to the
individual layers, and between the major surfaces in a flat profile
battery design.
Limitations on layer thickness are primarily based on manufacturing
considerations, and mask-to-mask (or roll to roll) variations.
There may also be a relationship between anode and cathode
thickness and ion transport capability. Where thicker anode and
cathode layers may be achieved by silk screening or other
lamination methods 50, edge deterioration effects may be mitigated
using a conformal coating or encapsulant to seal the edges of the
battery core, as described above.
FIG. 6A is a cross-sectional illustration of cathode layer 34 for a
laminar battery core, for example battery core 28 of FIGS. 1-4. A
relatively thick layer of cathode material 34 is deposited on
cathode substrate 39, for example lithium cobalt oxide material
using a masking or screening process, as described above, or via
another process such as sputtering or chemical vapor deposition
(CVD). Encapsulant or conformal coating material 16 may be applied
to seal the sides or edges of cathode layer 12.
A separator/electrolyte or ion transport layer 36 can be deposited
on top of cathode layer 34, opposite cathode substrate layer 39.
Depending upon application, a lithium phosphate, lithium
phosphorous, or lithium phosphorous oxynitride (LiPON or
LiPO.sub.xN.sub.y) material may be utilized for separator layer 36,
for example to replace the traditional lithium ion transfer
electrolyte and separator material with a glassy or thin film solid
electrolyte separator layer 36. In additional configurations, a
lithium polymer battery configuration may be utilized, using a
lithium-salt type electrolyte in a substantially solid polymer
composite for separator layer 36.
FIG. 6B is a cross-sectional illustration of anode and cathode
layers 32 and 34 for laminar battery core 28. Anode layer 32 is
formed on separator layer 36, opposite cathode layer 34, for
example by physical vapor deposition (PVD) or powder deposition of
a lithium material. Alternatively, anode layer 32 may be formed of
different material such as graphite, and anode layer 32 may be
applied via a screening or masking method, for example as described
above with respect to method 50 of FIG. 5.
FIG. 6C is a cross-sectional illustration of battery core element
60, including anode and cathode layers 32 and 34 separated by
separator layer 36. Battery core element 60 also includes anode and
cathode collector layers 37 and 39, as positioned adjacent to and
in electrical contact with anode and cathode layers 32 and 34,
respectively, opposite separator layer 36. Encapsulant or conformal
coating 16 and flexible sealant 62 are provided to seal the sides
of battery core element 60, including cathode layer 32, separator
layer 36, and anode layer 32.
Flexible sealant 60 may be formed of an insulating material such as
a room temperature vulcanizing (RTV) silicone or other silicone or
polymer-based material, or an encapsulant or conformal coating.
Similar, encapsulant 16 may be formed of a flexible sealant, such
as RTV silicone or other silicone or polymer based material.
FIG. 7A is a schematic illustration of core stack element 60,
illustrating different external connector configurations. As shown
in FIG. 7A, anode collector 37 may extend to external connection
point 37A on the same side of stack element 60 as cathode
collection point 39A, as defined for cathode collector 39.
Alternatively, anode collector 37 may extend to external connection
point 37B, on the opposite side of stack element 60 with respect to
cathode collection point 39A.
FIG. 7B is a schematic illustration of battery core 28, in a
single-side stack configuration. In this configuration, individual
stack elements 60 are stacked together in the same orientation,
with anode collectors 37 extending to anode connection points 37B
along one side of battery core (or stack) 28, and cathode
collectors 39 extending to cathode connection points 39A on the
opposite side of battery core (or stack) 28. This allows all the
cathode lines to be coupled to a single cathode output, and all the
anode lines to be coupled to a single anode output, thus making the
battery have a single cathode and a single anode.
FIG. 7C is a schematic illustration of battery core 28 in the
single-stack configuration, illustrating representative layer
thicknesses (in microns). In this particular configuration, cathode
layer 34 has a thickness of about 10 microns, or about 25% of the
total stack thickness of about 40 microns, including two conformal
coating or encapsulation layers 16 of about 3 microns each, anode
and cathode collector layers (or substrates) 37 and 39 of about 8
microns each, separator layer 36 of about 2 microns, and anode
layer 32 of about 6 microns.
This results in a net or average cathode stacking efficiency of
about 25% or more for battery core (or stack) 28, as defined by the
fraction of the battery thickness occupied by cathode layers 34.
This result is substantially higher than in other battery designs,
providing battery core 28 (and battery 10) with greater energy
storage density and capacity. In thicker embodiments, cathode layer
34 may have a thickness of up to 25 microns or more, or more than
40% of the total stack thickness, for example about 45% of the
total stack thickness.
FIG. 8 is a schematic illustration of battery core (or core stack)
28 in a double-sided stack configuration. In this example, one core
or stack element 60 is inverted with respect to the other, as
described above with respect to FIG. 3, using a single cathode
collector 39 between two adjacent cathode layers 34. In this
configuration, the vertical cathode efficiency may be about 30% or
more (about 30.3%), based on two cathode layers 34 with a total
thickness of about 20 microns, in a stack with two anode layers 34
at about 6 microns each, two separator layers 36 at about 2 microns
each, two conformal coating layers 16 at about 3 microns each, two
anode collectors 37 at about 8 microns each, and only one cathode
collector 39 at about 8 microns (about 66 microns total). For
thicker cathode designs of up to 25 microns or more, the cathode
stacking efficiency may be higher, for example about 50% or
more.
FIG. 9 is a schematic illustration of battery core or stack 28 in a
single-sided, double stack configuration. This is similar to the
example of FIG. 8, but with stack elements 60 inverted so that a
single anode collector 37 is positioned between two adjacent anode
layers 32. The relative stacking thicknesses are approximately the
same, as described above with respect to FIG. 8, resulting in a
vertical cathode stacking efficiency of about 30% (or 30.3%)
FIG. 10 is a schematic illustration of battery core or stack 28, in
a multi-stack configuration. In this particular example, battery
stack 28 includes two separate instances of the single-sided,
double stack configuration of FIG. 9. Alternatively, battery stack
28 may comprise one, two, three, four or more core stack elements,
using any of the stacking configurations shown in FIG. 3, 4, 7A-7C,
8, or 9.
The foregoing description, for purposes of explanation, used
specific nomenclature to provide a thorough understanding of the
invention. However, it will be apparent to one skilled in the art
that the specific details are not required in order to practice the
invention. In other instances, well known circuits and devices are
shown in block diagram form in order to avoid unnecessary
distraction from the underlying invention. Thus, the foregoing
descriptions of specific embodiments of the present invention are
presented for purposes of illustration and description. They are
not intended to be exhaustive or to limit the invention to the
precise forms disclosed, obviously many modifications and
variations are possible in view of the above teachings. The
embodiments were chosen and described in order to best explain the
principles of the invention and its practical applications, to
thereby enable others skilled in the art to best utilize the
invention and various embodiments with various modifications as are
suited to the particular use contemplated. It is intended that the
scope of the invention be defined by the following claims and their
equivalents
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